For the further processing stages of printed products as from the printing press or intermediate products produced therefrom, it is necessary to in each case form into a group a specific number of different products of this type. Typical examples are the compilation or collection of different printed products for producing books or booklets or the insertion of different inserts or supplements in folded newspapers. Apparatuses, which e.g. combine into a flow of printed product groups a number of printed products entering in scale formation form are known. They conventionally comprise a plurality of feed or supply units, e.g. winding stations or feeders and a grouping unit, e.g. an insertion drum. Such apparatuses are e.g. described in U.S. Pat. Nos. 4,471,953 and 5,052,667.
Such apparatuses are e.g. monitored, in that each group is checked for the correct thickness. Groups which do not satisfy this inspection are then identified and usually extracted. As the extracted groups are caused by different errors in the supply or grouping, they have different forms or compilations and can consequently only be automatically divided up into the individual products and returned to the production line with considerable apparatus expenditure. Therefore these faulty groups are usually either completed by hand or sorted out for the return of the individual product, or are not returned to the production line. These faulty groups always constitute a material and/or personnel-intensive point in the production sequence.
The described disadvantage of the prior art methods and apparatuses for forming groups from different printed products and for checking the said grouping becomes a significant problem when it is a question of modifying the formation of the groups to be formed with high frequency, e.g. for each individual group and coordinating this change with further processing stages.
This is necessary if, in newspapers which are to be addressed, the individual groups of supplements, i.e., corresponding to the individual addresses, have to be inserted, a grouping process known as personalized insertion. An apparatus for forming individual groups of printed products is described in U.S. Pat. No. 3,966,186 (Helm). Using existing methods and apparatuses faulty groups resulting from errors in the supply of the individual products can only be recognized after grouping and eliminated only just prior to addressing, when the grouping unit is already dealing with the formation of subsequent groups. Thus, not only do faulty groups have to be further processed in a complicated and costly manner as described hereinbefore, but also the eliminated groups are missing from the addressing sequence and must be re-formed at a later time. However, if packing directly follows addressing and the addressing sequence is matched to a packing sequence, the grouping errors are propagated via the missing addresses to the packing stage and the aim is to avoid such a propagation of errors.